Stoker attachment



April 1, 1930.

R. s. HUGHES STOKER ATTACHMENT Filed April 6, 1929 HH H "l l l l n m M I gwuemtoo Patented Apr. 1, 1930 UNITED STATES ROBERT H. S. HUGHES, OF BALTIMORE, MARYLAND STOKER ATTACHMENT Application filed April 6, 1929. Serial No. 353,139.

This invention relates to stokers for furnaces in which fuel fed automatically from a hopper to the furnace chamber by a conveyer. In the operation of such stokers, with 5 some kinds of fuel, the fuel is apt to stick in the hopper and to arch over the conveyer, and when this occurs the feed of fuel from the hopper to the furnace is irregular, or it may stop altogether.

The purpose of the present invention is to provide simple and effective means for preventing the fuel from sticking and arching in the hopper. I have found that the adherence of the finer particles of fuel, particularly if moist, to the walls of the hopper,

is a main cause of the clogging of the hopper, and I have therefore provided means operated by the conveyor for vibrating the hopper walls in order to loosen the fuel which is on and adjacent the Walls. The means preferably employed for vibrating the hopper Walls comprises one or more resilient y rods secured at their upper ends to the walls of the hopper at opposite sides of the axis of thee conveyer and extending downwardly through the hopper into position to be moved and tripped by the conveyer, to jar the hopper walls. As these rods extend throu h the body of fuel in the hopper, it will be evident that they will also agitate the mass of fuel so that if the fuel has any tendency to arch over the conveyer, this agitation will prevent arching.

In the accompanyin drawing, Fig. 1 is a section through part of a. furnace to which is applied a mechanical stoker havmg my improvements therein, the stoker being shown inside elevation partly broken awa Fig. 2 is a central vertical section through the fuel hopper and conveyer, taken longitudinally of the latter; and, Fig. 3 is a section through the fuel hopper on the line 33 of Fig. 1. v

Referring to the drawing, (1 indicates the V combustion chamber of a furnace, and b indicates a mechanical stoker comprising a fuel hopper 1, a pipe 2, leading from the lower part of the hopper to a firepot 3, and'a screw conveyer 4 in the pipe for carrying the fuel from the hoper to the firepot. The screw conveyer is rotated very slowly by an electric motor (not shown), and reducing gearing contained in a casing 5. Air'is supplied to the furnace through a conduit 6 a from a blower 7.

In the operation of the stoker, a supply of fuel, such as soft coal, is placed in the hopper and the conveyer feeds this fuel to the furnaee as fast as it is required, the speed of the motor which drives the conveyer being regulated by temperature-eontrollin devices, in well known manner. As the fuel is carried from the bottom of the hopper, if the, coal sticks in the hopper and arches over the conveyer screw, the supply of coal to the furnace will be irregular or may stop alto gethe'r.

I have found that the adherence of the fuel, particularly if moist, to the side walls of the hopper is a main cause of the clogging of the hopper, and I have therefore provided simple means for vibrating the side walls of the hopper, to loosen the fuel therefrom, and by the same means the mass of fuel in the hopper is agitated so that the tendency of the fuel to arch is avoided.

In carrying out the invention, I provide one or more resilient devices, secured to the upper portions of the side walls of the hopper,-that is, the'walls which are at opposite sides of the axis of the conveyer, and extending' downwardly in the hopper into position to be put under tension by the convolutions of the conveyer, and then tripped, with the result that the side walls of the hopper, which are formed of sheet metal, are placed under strain while the resilient device is being moved by the conveyer to the tripping position, and when the strain is relieved these walls vibrate and the fuel is loosened from their surfaces and archingofthe fuel over the conveyer is prevented. To add to this effect, these devices may be arranged so that when'tripped they will strike the wall of the hopper. As these resilient devices extend downwardly through the hopper, they also agitate and break up the mass of fuel in the center of the hopper when moved and tripped by the conveyer.

The resilient devices referred to may take various forms. In the drawing, I have shown two such devices 8 and 9, which are alike except that the device 8 is curved so that the 5 part contained between its ends normally lies against the rear wall 3* of the hopper. The device 8, composed'of a metal rod 8, is twisted at the center, as shown at 8, and the two halves 8* of the rod diverge from the center.

10 The ends of these halves or arms 8 are secured rigidly to the upper'lparts of the side walls 1 and 2 of the hopper, while the twisted central portion 8 lies in'th'e path of movement of the convolutions of theconveyer 4. The arms 8 may be connected by cross-pieces 8 for strengthening the device, and also for assisting in breaking up the mass of fuel.

' The arms extend downwardl from their points of attachment to the side walls and 2 are bent, below the cross-pieces 8, so as to lie against the back wall of the hopper.

The resilient device 9 is substantially the same as the device 8, but it shown straighter- 7 and its ends are connected to the side walls of the hopper adjacent the front wall, and it does not lie against the wall as does the de- Vice 8. In operation, the conveyer turns in the direction indicated by the arrow in'Fig. 2, and

the convolutions of the-conveyer, engaging the heads 8 and 9 of the rods 8 and 9, move these heads to-the left and put the rods under tension and to. some extent warp the side walls of the hopper. As the conveyer continues to.

rotate, each headfinallytripsrger the convolution which it engages and the rods spring backward, relieving the strfiik on' the side walls of the hopper and causing them to vibrate. The rod 8 alsostrikes the latter wall 0 3, thus amplifying the vibrations. Of course, if the fuelisgfeeding properly from -the hopper, so tha t the spacesibetween the convolutions of the screw are filled with fuel, the resilient devices will not spring back to their normal positions with great force because their movements will be obstructed by the fuel; but if the downward movement of the fuel in the hopper becomes slightly slug gish, so that the fuel is not well packed around the conveyer at the bottom of the hopper, the resilient devices will snap back vigorously, shaking the walls of the hopper and also loosening the mass of fuel between the walls, so that the tendency of the fuel to clog'and arch will be overcome.

a What I claim is: 1. In a stoker, a fuel hopper having sheet metal walls, a fire pot, a pipe leading from the former to the latter, a screw conveyer in i 6 the hopper and pipe and means for vibrating one of the hopper walls at one side of the axis of the conveyer comprising a resilient member secured to said wall and extending downwardly through the hopper into posi-- tion to be moved and tripped by the convolutions of the conveyer, said member, while I being moved to the tripping position, adapted to put said wall under strain.

2. In a stoker, a fuel hopper having sheet metal walls, a fire pot, a pipe leading from the former to the latter, a screw conveyer in the ho per and pipe and means for'vibrating one of axis ofthe conveyer comprising a resilient member secured to saidwall and extending downwardly through the hopper into posi- 1 tion to be moved and tripped by the convolutions of the conveyer, said member, while being moved to the tripping position, adapted to put said wall under strain and adapted, when tripped, to strike the hopper.

' 3. In a stoker, a fuel hopper having sheet metal walls, a fire pot, a pipe leading from the hopper walls at one sideof the the former to the latter, a screw conveyer in.

the hopper and pipe and means for vibrating the walls of the hopper located at opposite sides of the axis of the conveyer comprisin a V-shaped rod secured at its ends to sm walls and extending downwardly through I the hopper into position to, be moved and tri ped by the convolutions of the conveyer, said rod, while being moved to the trlpping position, adapted to put said walls under strain.

4. The combination with a furnace, of a stoker comprising a fuel hopper having sheet and adapted to be moved and tripped by the conveying means, said member, while being moved to thetripping position, adapted to put said wall under strain.

In testimony whereof I afiix my s1 nature.

ROBERT H. S. HUG ES. 

